diff --git a/Gemfile b/Gemfile
index d892ff3..99a7c05 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ end
 gem 'rails', '~> 5.1.6.2'
 # Use sqlite3 as the database for Active Record
 # Use Puma as the app server
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 0f04219..f9ccbbe 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -125,7 +125,8 @@ GEM
     postgresql (1.0.0)
       pg
     public_suffix (3.0.3)
-    puma (3.12.3)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -233,7 +234,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   jquery-rails
   postgresql
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.1.6.2)
   sass-rails (~> 5.0)
   selenium-webdriver